21 replies to this topic

[Ethel]

Timmy's made me think of another option - programmable ignition. Being able to get the timing much nearer the money than you can with a clockwork dizzy will give a good improvement in tractability everywhere as well as reliability & economy.

 

Metty Turbo had a 3.2 FD which, I think, was resurrected on the SPI Mini.

 

 

Light flywheels are near enough essential on racers, where getting to the first corner in front of the competition really matters. As has already been said, the benefit is a lot less dramatic doing road car type stuff

[babsbrown]

Thanks for your input gents,
If I was to go pre verto, I imagine I'll have to fit a new longer clutch arm?

[timmy850]

I wouldn't bother swapping back to pre-verto. You need a new flywheel, clutch plate, diaphragm, throw out bearing, plunger, clutch arm, slave cylinder etc

[babsbrown]

I am sure lightened pre-Verto is the way to go combined with a 3.44 fdr.
If you know that the bottom end bearings and oil pump are good, then it’s easy to change the diff with the engine on the box. Just remove the end cover and diff cover. A cross pin diff is a good idea as well.

Thanks cooperman,

I have just rebuilt the engine and gearbox, unfortunately not with a x pin, but the uprated kit by minispares. The engines fully installed now, so I imagine to do this with the engine in would be just as much faffing as removing the engine and doing it whilst out

[babsbrown]

My 1098 has 3.44 diff and a lightened pre-verto flywheel.

If I was going to change the diff ratio either way I'd go for something longer like a 3.1, or in-between 3.44 and 3.1 using some different drop gears.

However, with standard ratio gears, a low final drive ratio (like 3.1) and using less than 6000rpm you'd have a big RPM drop between each gear and it'd feel flat when you change gear and drop back in rpm

What's your timing curve like at 2000rpm?

Mine happily revs well past 6000rpm, I currently have an rpm limiter on at 6000rpm to keep it under control.
https://youtube.com/shorts/yCJE_DkMf8s

Thanks timmy, that sounds awesome!! Timing is around 20 degrees at 2000rpm.
It's a coincidence, I have been looking at distributors recently too. Advised that the evo dizzy thats set up for my cam should be back In stock this week at minispares. But I'm getting impatient and might just get the CSI programmable one. What CR are you running on your 1098? If I remember rightly it's +60 with flat tops?

[timmy850]

Mine is now 10.5:1 and it's +080 with an RE266SS cam. The most expensive part of the build was the modified 12G202 head which is probably where most of the advantage comes from.

 

I have a programmable advance unit and it's 20 degrees at 2000rpm

[babsbrown]

Mine is now 10.5:1 and it's +080 with an RE266SS cam. The most expensive part of the build was the modified 12G202 head which is probably where most of the advantage comes from.

I have a programmable advance unit and it's 20 degrees at 2000rpm

Ah nice, it sounds lovely. We're you running twin hs2s in that video? Do you find them adequate for the engine size?